A243069 a(n) = smallest natural number that has not yet occurred among the first n terms of A126917.

2, 3, 4, 4, 6, 6, 7, 7, 7, 7, 9, 9, 12, 12, 12, 12, 13, 13, 15, 15, 15, 15, 16, 16, 16, 16, 16, 16, 19, 19, 21, 21, 21, 21, 21, 21, 22, 22, 22, 22, 27, 27, 28, 28, 28, 28, 30, 30, 30, 30, 30, 30, 31, 31, 31, 31, 31, 31, 36, 36, 37, 37, 37, 37, 37, 37, 39, 39, 39, 39, 42, 42, 45

Offset: 1

Author

Antti Karttunen, Jun 20 2014

Keywords

• nonn

Comments

Facilitates the computing of A126917.

a(n) grows only when n is a prime. A243498 gives the values at those points.

Examples

			The first eight terms of A126917 are: 1, 2, 3, 5, 4, 8, 6, 11. In range [1,1] the first that has not yet occurred is 2, in range [1,2] it is 3, in range [1,3] it is 4, in range [1,4] it is still 4, in range [1,5] it is 6, in range [1,6] it is still 6, in range [1,7] it is 7, in range [1,8] it is still 7, thus the first eight terms of this sequence are 2, 3, 4, 4, 6, 6, 7, 7.
		

Links

• Antti Karttunen, Table of n, a(n) for n = 1..10000

Crossrefs

Cf. A126917, A126918, A243488, A243498.

Formula

For all n, a(n) <= A126917(n+1).

For n >= 2, if A126917(n) > a(n-1) [when n is composite], a(n) = a(n-1).